Control of the short-term dynamics of intertidal microphytobenthos by the exondation-submersion cycle

We test herein the hypothesis that the succession of low tides - during which biomass increases - and high tides - during which biomass decreases - controls the dynamic behaviour of the microphytobenthic compartment. Results indeed show that during a complete lunar cycle (14 d) biomass exhibits a series of oscillations due to biomass increases during low tides and decreases during high tides. Moreover, the datasets show that the production level is in the range of previously recorded values and they indicate that the major part of the photosynthetically produced biomass during low tide can be exported into the water column during high tide. This dearly suggests that microphytobenthos is the major autochtonous source of organic matter production in the littoral zone and that it directly supplies the associated pelagic trophic web. ((C) Academie des sciences / Elsevier, Paris.).